Editing Cluster of differentiation (section)

==Immunophenotyping==
[[File:Cluster of differentiation.svg|thumb|Cluster of Differentiation]]
The CD system is commonly used as cell markers in [[immunophenotyping]], allowing cells to be defined based on what molecules are present on their surface. These markers are often used to associate cells with certain [[immune system|immune function]]s. While using one CD molecule to define populations is uncommon (though a few examples exist), combining markers has allowed for cell types with very specific definitions within the immune system.{{citation needed|date=May 2020}}

CD molecules are utilized in [[cell sorting]] using various methods, including [[flow cytometry]].{{cn|date=December 2024}}

{| class="wikitable"
! Type of cell !! CD markers
 |-
 | [[stem cell]]s || [[CD34]]+, [[CD31]]-, [[CD117]]
 |-
 | all [[leukocyte]] groups || [[CD45]]+
 |-
 | [[Granulocyte]]  || CD45+, [[CD11b]], [[CD15]]+, [[CD24]]+, [[CD114]]+, CD182+<ref name="docs.abcam.com">{{Cite web |year=2009 |title=CD Antigens |url=http://docs.abcam.com/pdf/immunology/cdantigen_poster.pdf |access-date=2014-11-22 |publisher=abcam}}</ref>
 |-
 | [[Monocyte]] || CD4, CD45+, [[CD14]]+, [[CD114]]+,  [[CD11a]], CD11b, CD91+,<ref name="docs.abcam.com" /> [[CD16]]+<ref>{{Cite journal |vauthors=Passlick B, Flieger D, Ziegler-Heitbrock HW |year=1989 |title=Identification and characterization of a novel monocyte subpopulation in human peripheral blood |journal=[[Blood (journal)|Blood]] |volume=74 |issue=7 |pages=2527–2534 |doi=10.1182/blood.V74.7.2527.2527 |pmid=2478233 |doi-access=free}}</ref>
 |-
 | [[T lymphocyte]] || CD45+, [[CD3 (immunology)|CD3]]+
 |-
 | [[T helper cell]] || CD45+, CD3+, [[CD4]]+
 |-
 | [[T regulatory cell]] ||[[CD4]], [[CD25]], [[FOXP3|FOXP3 (a transcription factor)]]
 |-
 | [[Cytotoxic T cell]] || CD45+, CD3+, [[CD8]]+
 |-
 | [[B lymphocyte]] || CD45+, [[CD19]]+, [[CD20]]+, [[CD24]]+, [[CD38]], [[CD22]]
 |-
 | [[Thrombocyte]] || CD45+, [[CD61]]+
 |-
 | [[Natural killer cell]] || [[CD16]]+, [[CD56]]+, CD3-, [[CD31]], [[CD30]], CD38
|}

Two commonly used CD molecules are [[CD4]] and [[CD8]], which are, in general, used as markers for [[T helper cell|helper]] and [[cytotoxic T cell|cytotoxic]] T cells, respectively. These molecules are defined in combination with CD3+, as some other leukocytes also express these CD molecules (some macrophages express low levels of CD4; [[dendritic cells]] express high levels of CD8). [[Human immunodeficiency virus]] binds CD4 and a [[chemokine]] receptor on the surface of a T helper cell to gain entry. The number of CD4 and CD8 T cells in blood is often used to monitor the progression of [[HIV infection]].{{cn|date=December 2024}}